So, the next question is: will any of the projects run for me out of the box, or at least compile with minimal tweaking? I don't mind it being in Verilog, but I don't like giving up, so want to see one of these boards mining!
What project file would you suggest I use as a staring point? I tried the "LX150 makomk....." projects, but they resulted in thousands of warnings (just opened the project and clicked the build button).
I never had any of the SLX150 boards that were used in those projects. I built some of them with minor changes on VLX240; but I don't recall which ones. This design is very flexible: you can roll the hashers by increasing CONFIG_LOOP_LOG2 parameter until it fits in your Spartan. You shouldn't worry about warnings; there is no way to completely shut them down in ISE even for a perfect design.
This project isn't friendly for simulation. The I/O protocol would need to be changed to give beginning and end of the nonce range to search. Otherwise simulating the search through the 2^32 nonce values just takes too much real time.